In recent years, technological innovation in the moving image field such as televisions and the like is remarkable, and the quality of moving images is improving.
Conventionally, a normally used display format of moving images adopts a frame rate of 30 frames/sec. In recent years, a display format having a frame rate as high as 60 frames/sec is also available.
In practice, in a normal display (e.g., playback of video-recorded data in a normal mode), 30 frames/sec can assure sufficiently high moving image quality, and many users consider that the frame rate of 60 frames/sec is not necessary. Of course, the frame rate of 60 frames/sec can assure higher image quality. However, the human eye does not accurately recognize these 60 frames, and recognizes a moving image with sufficiently high quality even at 30 frames/sec.
When a moving image is recorded at 60 frames/sec, the load on a decoder (a CPU in case of a computer) that decodes the recorded image (encoded moving image data) is heavier than decoding of encoded moving image data recorded at 30 frames/sec.
On the other hand, in a slow playback mode, a generally known moving image of 30 frames/sec is insufficient. When a moving image of 30 frames/sec is played back in a slow playback mode, an image is displayed frame by frame.
In encoding of a moving image, MPEG-2, MPEG-4, and MotionJPEG2000 as encoding schemes having hierarchy are beginning to prevail, and many moving image playback apparatuses compatible to these moving image formats are being developed accordingly.
A moving image playback apparatus which plays back such hierarchical moving image data has been developed. However, a moving image playback apparatus which can display each frame with higher image quality than a playback image in a normal playback mode while utilizing hierarchy of the moving image data in a slow playback function that allows the user to recognize details of each frame is not available at this moment.